Saturday, February 24, 2018

Rose Point Navigation's Nemo Interface

I've been using Rose point Navigation's Nemo interface for 2 years now, initially as an Alpha/Beta test customer, then as a full paying customer.  And I continue to test new releases since I seem to have special skills when it comes to breaking things...

- Nemo is essentially the interface to all your marine electronics. It connects to your marine electronics using the two standard interfaces (NMEA 2000 and NMEA 0183), and connect to your computer via ethernet.

- Because it connects to your computer via ethernet and not USB or serial ports, it actually works reliably. No drivers are required, which is the source of most evil in Windows.

- The NMEA 0183 interfaces are correct RS-422 interfaces, not RS232 which so many people use. The two are NOT the same, and are NOT compatible by design and by specification. Using RS232 to interface to marine electronics is just asking for a flaky, unreliable system.

- It supports four 0183 inputs, so you can bring in data from a number of sensors without requiring external multiplexers. This reduces complexity, reduces the number of failure points, and reduces cost.

- It supports two 0183 outputs. This lets you directly control an autopilot via 0183, and other devices as well.

- In addition to interfacing all your data to Coastal Explorer, Nemo also sends the data on ethernet using a de-facto UDP standard. Other devices on your network can pick up and use this data, like iPad apps, Coastal Explorer running on a laptop, etc.

- It has excellent NMEA 2000 support including superior source data selection. With N2K, all data from all sensors is on the network at the same time. As a result, it's up to each listening device to decide which sensors it wants to use. This is referred to as Source Selection, and some vendors do it a lot better than others. The simplest devices will automatically pick one of each sensor type, and typically they will fail over to another if the first fails. But you have no control over which it picks.

Better devices present you with a list of available devices and let you pick which you want to use. At least this lets you ensure the system is using the best of each device type that you might have. If the selected sensor fails, some will automatically switch to something else, where others require you  make a new choice.

The best devices present you with a list of available sensors and let you prioritize their use, picking which you want to be primary, which is secondary, and so fourth. Coastal Explorer and Nemo do this better than anyone else, allowing you to prioritize any arbitrary number of devices. The only other product I've encountered that comes close it the Furuno NavPilot which let's you prioritize up to three devices for each data type.

- Nemo passes "native" N2K data back and fourth between Coastal Explorer and the N2K network. This means that the actual N2K messages pass through to Coastal Explorer and it processes and interprets them. And Coastal Explorer sends N2K messages which nemo relays to the N2K network. LOTS of other N2K interfaces don't do this, but rather translate between N2K and 0183, communicating with the computer only via 0183. Translation between the two is NOT 1 for 1, and can sometimes be quite messy. Plus you lose all ability to do source selection for your N2K sensors. Nemo does this correctly.

- Nemo can also translate between its 0183 and N2K interfaces. This provides a bridging function between the two that otherwise requires dedicated converter devices. And it does this translation MUCH better than any other device that I've used, allowing you to select individual sentences/PGNs that you want translated, selecting the update frequency, and of course using proper source selection. I have not seen any other device that can do this.  With this translation function, I have eliminated four dedicated converters from my electronics suite.

- Nemo might seem expensive (list price $699), but when you look at what it replaces, it's a real bargain. First, if you are going to add proper RS-422 data interfaces to your PC, it's going to cost you.  Yes, you can get RS-232 USB adapters for about 5 cents each, but remember, they are not compatible with NMEA 0183, and although they will probably appear to work, it will be unreliable. I used one once in a pinch, and all seemed to work OK. But when I looked at the actual sentences being received by Coastal Explorer, a significant portion of them were corrupted. Enough made it through OK for things to mostly work, but do you really want corrupted data running around you navigation system? I sure don't.

Anyway, an ethernet-connected 4 port RS-422 interface can cost $300-$500. So right there is probably 60% of the cost.

Then an N2K interface will cost another $200 or so, and they are all USB connected. That means they only work with the computer they are plugged into, and you have the associated driver nightmares. Nemo gives you the same capability, plus more. The data is on the network, so any Coastal Explorer  (or other) systems can see it. And you are spared the windows driver fiasco. At this point you have pretty much covered the cost of Nemo.

Oh, and because Nemo puts the data on the network, it eliminates the need for one of the many devices that do that as a dedicated function. There's another couple hundred $$ saved.

Then, if you have any data translation conversion required between N2K and 0183, then you really start coming out ahead with Nemo. I have already replaced four $200 converters, and expect to replace two more. That's $800 worth of converters eliminated

- And in good Rose Point fashion, the product is reliable, simple to use, easy to update over the internet, etc.

When you consider what you get for the $$ you spend a dedicated chart plotter, or how much more software like MaxSea costs, and how it solves none of the data interfacing problems, I think Coastal Explorer + Nemo is a real bargain, and one of the best performing products I have used in a long time.


  1. Hi Peter,

    This sounds like a very good combo. Does the Nemo also support combining magnetic heading and variation to output true heading?

    I'm guessing electronics selection for your new boat is some way off, but in case it's of interest. There seems to be a relatively new standard (for ships rather than yachts) that enables the "transport of NMEA sentences as defined in 61162-1 over IPv4" *. It's called IEC 61162-450 (NMEA 0183 is IEC 61162-1) and nicknamed Lightweight Ethernet. Recent commercial Furuno equipment like the SC-70, the GP-170 and the FAR-22x8 support it in addition to NMEA 0183.

    On the other hand, the worst case of three different networks... :)


  2. Yes, Nemo can combine magnetic heading and variation to create true heading. This is important if you want to use a magnetic compass for a Class A AIS or and IMO radar, both of which require true heading. I'm using it to do just that so I can use a magnetic compass as a backup for my sat compass.

    That's interesting about 0183 over IP being standardized. I knew there was a defacto standard, and wonder if it's the same thing, but formalized. I'll have to check it out. Thanks for the tip!

  3. According to the Nemo page, it already supports NMEA data over TCP (presumably output only), but no mention of IEC 61162-450 support, unfortunately.

  4. Peter: is there any reason NEMO won't work with MaxSea TimeZero Navigator (or Nobeltec equivalent)? I know you are not a MaxSea fan...but I am and would like to use Navigator instead of CE. Is this possible?


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